Orofacial proprioceptive thalamus of the rat.

The ascending pathway mediating proprioception from the orofacial region is still not fully known. The present study elucidated the relay of jaw-closing muscle spindle (JCMS) inputs from brainstem to thalamus in rats. We injected an anterograde tracer into the electrophysiologically identified supratrigeminal nucleus (Su5), known to receive JCMS input.

Direct projection from the lateral habenula to the trigeminal mesencephalic nucleus in rats.

Trigeminal mesencephalic nucleus (Vmes) neurons are primary afferents conveying deep sensation from the masticatory muscle spindles or the periodontal mechanoreceptors, and are crucial for controlling jaw movements. Their cell bodies exist in the brain and receive descending commands from a variety of cortical and subcortical structures involved in limbic (emotional) systems. However, it remains unclear how the lateral habenula (LHb), a center of negative emotions (e.